High pressure growth and electron transport properties of superconducting SmFeAsO1-xHx single crystals

We report the single crystal growth and characterization of the highest T-c iron-based superconductor SmFeAsO1-xHx. Some sub-millimeter-sized crystals were grown using the mixture flux of Na3As + 3NaH + As at 3.0 GPa and 1473 K. The chemical composition analyses confirmed 10% substitution of hydrogen for the oxygen site (x = 0.10), however, the structural analyses suggested that the obtained crystal forms a multi-domain structure. By using the FIB technique we fabricated the single domain SmFeAsO0.9H0.10 crystal with the Tc of 42 K, and revealed the metallic conduction in in-plane (rho(ab)), while semiconducting in the out-of-plane (rho(c)). From the in-plane Hall coefficient measurements, we confirmed that the dominant carrier of SmFeAsO0.9H0.10 crystal is an electron, and the hydride ion occupied at the site of the oxygen ion effectively supplies a carrier electron per iron following the equation: O2- -> H- + e(-). (C) 2017 The Ceramic Society of Japan and the Korean Ceramic Society. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.